iPhone 13 keeps brightening up photos and videos when viewing on apps?

So I thought this was an app specific problem for a while but I've noticed it happening in many different apps. When I've turned my brightness down on my phone and I scroll through apps such as instagram/Reddit, photos and videos will often auto brighten up to full brightness to the point that it hurts my eyes and has given me a headache before. It's just the photo/video and not the whole screen, and when I scroll past it, it goes back to normal. And it doesn't always do it for every photo/video.

ive looked in app and display settings and can't find anything that changes it and when I've googled it nobody else seems to have this issue. Any help appreciated pls